Solid-state laser systems are characterized in that they have a solid-state laser gain medium which converts energy from an optical pump source to a coherent output laser beam. The pump source can be one of many available energy-producing systems such as flash lamps or semiconductor laser diodes. The energy produced by the pump source is incident upon the laser medium and absorbed by the laser medium.
The absorbed energy in the laser medium causes the atoms in the laser medium to be excited and placed in a higher energy state. Once at this higher state, the laser medium releases its own energy which is placed into an oscillating state by the use of a laser resonator. The laser resonator includes at least two reflective surfaces located on either side of the laser medium. The laser resonator may be designed to continuously release a laser beam from the system. Alternatively, the resonator can be designed such that when the energy oscillating through the laser medium reaches a predetermined level, it is released from the system as a high-power, short-duration laser beam.
In many systems, the laser medium is Neodymium-doped, Yttrium-Aluminum Garnet (Nd:YAG). A laser medium made from Nd:YAG absorbs optical energy most readily when the energy is at a wavelength of approximately 808 nanometers (nm). Thus, the source to pump the Nd:YAG laser medium should be emitting light energy at approximately 808 nm. Gallium arsenide semiconductor laser diodes can be manufactured with dopants (e.g. aluminum) that will cause the emitted light to be in a variety of wavelengths, including 808 nm. Thus, the semiconductor laser diodes, which are lasers by themselves, act as the pump source for the laser medium.
The emitted light produced from the solid-state laser system is generally coherent and exits the system in a predefined area. Thus, the optical power produced can be readily focused by the use of other optical components such as lenses. The resultant emitted energy can be used for a variety of industrial, medical, and scientific purposes such as cutting material, melting materials, ablating materials or vaporizing materials.
It has been an objective for laser manufacturers to develop high-power, solid-state systems that can be packaged in small housings. However, this objective is difficult to meet due to the large amount of waste heat produced by these systems and the necessity for large areas in which to provide adequate cooling. As the output power in these systems increases, the waste heat increases which puts more demands on these cooling systems.
Furthermore, these laser systems are often used in settings, such as laboratories, which are equipped with devices for mounting other types of laser systems, such as gas lasers. A basic type of gas laser is a Helium-Neon ("He--Ne") laser which has a relatively low output power, usually less than 0.1 Watt. Because the waste heat produced by a He--Ne laser is small, the system can be air-cooled and can be efficiently packaged in a simple cylindrical housing. These cylindrically-packaged He--Ne lasers are mounted in several styles of laser mount structures which provide for easy adjustment of the output beams.
Another type of laser that is mounted in a small cylinder is a single-emitter, semiconductor laser diode. However, the output powers on these devices are usually less than about 0.5 Watt. Like the gas laser, this system relies on air cooling